#15136: High CPU when asynchronous exception and unblocking retry on TVar raced -------------------------------------+------------------------------------- Reporter: nshimaza | Owner: (none) Type: bug | Status: new Priority: highest | Milestone: 8.6.1 Component: Runtime System | Version: 8.4.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: Runtime crash | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by simonmar): Thanks for the excellent diagnosis @bgamari. I'm not sure what the best fix is yet, but there is something distinctly strange here. `lockTSO` and `unlockTSO` are only used to synchronise for this particular case, between `raiseAsync` and `unpark_tso`. In all other cases, a TSO has a clear owner - in the case of a blocked TSO, the owner is usually the object on which the TSO is blocked, e.g. an MVar. Perhaps we should switch to using an owner semantics for BlockedOnSTM too - that is, if we see `BlockedOnSTM` in `raiseAsync`, we attempt to lock the `TVar` pointed to by `tso->block_info`. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15136#comment:5 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler